This invention relates to spreader rolls, in particular to a new and improved device of this type which overcomes the difficulties experienced using the usual devices.
Spreader rolls are used on machines for the manufacture of paper, plastic or other web-like material, and typically include a bowed or adjustably bowable, non-rotatable shaft and an a outer roll surface mounted for rotation on the shaft. Generally, the outer roll surface is composed of a plurality of individual, longitudinally aligned, interconnected cylinder elements. These are often referenced to as roll segments.
In the production of web-like material, such as paper, a machine produces the web product on large rolls, which are cumbersome to handle and hence must be cut down to a smaller, usable size. In order to reduce the size of the initially produced large web, the roll of a large web may be rewound onto a plurality of axially aligned cores of a predetermined length. As the web is wound from the large roll onto the cores, the web is split lengthwise to form a plurality of smaller webs having a predetermined width. This predetermined width corresponds to the width of the uptake cores, which are of a size desired by the end user. Prevention of overlap of the smaller webs between adjacent rolls on the rewinding device is critical, and therefore the slit web material is typically spread out, fanlike, by means of a spreader roll prior to rewind on the uptake cores. It is to be noted that a spreader roll is also useful, other than rewinding, to spread the web at numerous critical processes positions on web machines are related finishing and converting equipment.
A typical spreader roll is characterized by an arrangement of closely spaced and longitudinally arranged cylinder elements or segments rotatably supported on a stationary, bowed cylindrical shaft. The cylinder elements are typically held together, end-to-end, by a coupling and cleat combination to thereby present a substantially continuous cylindrical roll surface. Additionally, the cylindrical roll surface may be covered with a rubber composition.
The design of this type spreader roll has the disadvantage of producing a juncture or gap between the upper surfaces of adjacent cylinder elements. The gap at the juncture between adjacent cylinder edges is caused by the bow of the underlying shaft, which causes the upper surfaces of adjacent cylinder elements to be somewhat farther apart than the lower edges. This effect is caused by the incremental compensation of the total arc of the bow at every cylinder element juncture. The gaps created at the juncture between cylinder element edges create several disadvantages. For example, if use of a lightweight web material is desired, the web is prone to unwanted snagging on this gap between cylinder edges. This snagging is due to lack of web support at this linear junction, and is most notable during use of lightweight web material. Further, the linear gap between cylinder element edges often causes undesirable marking on the lightweight web surfaces contacting the spreader roll. Treatment of lightweight web material is particularly crucial in the paper industry, in which less expensive, lightweight paper stock is highly desired in the production of catalogues and mass-mailing pieces.
The present invention has as its objective to provide an improvement in the design of bowed spreader rolls, specifically the cylinder elements, and thereby ameliorate the above stated problems.
This objective is accomplished by the present invention of a spreader roll having cylinder rolls with novel mating end profiles.